Margaret Thatcher famously remarked that there is no such thing as society, only people and their families. Of course, she was wrong, as this blog remarked in the context of violence and pacifism. Read it here.

(For another criticism, think about the point Steven Pinker makes in “The Blank Slate” that the children of immigrants learn the language of their adopted homeland with the local accent, not that of their parents.)

New light on the similar argument sometimes made about international society – that it is made up of sovereign states – is shed in a book by Paul Collier, “The Bottom Billion”. This book has attracted attention for its recommendations on trade, aid and humanitarian interventionism, and I will probably post a comment on that subject here in due course (when I have finished reading the book). But in the meantime I couldn’t resist rushing into the blog with a couple of observations Paul Collier reports.

Strikingly there is the impact of civil wars on the spread of diseases. Civil war in a country is terrible and expensive (he comes up with an estimate of $64 billion as the cost of the average civil war) – but these costs are borne not only by the country concerned but by its neighbours. For example, one of the major consequences of any war is the displacement of non-combatants. This is particularly true of wars based on competing ethnic claims for territory – this is where the term ethnic cleansing came from. And when peoples are on the move, disease spreads too. This is for two reasons.

First, the destitute and the displaced are more vulnerable to outbreaks of the serious, and usually eradicated or at least suppressed, diseases such as cholera and typhoid. A population on the move with poor sanitation and hygiene will be at risk, and should such a disease break out, it will spread from the moving population to the static peoples through which they are passing.

The second reason for the spread of disease is that any population will carry a set of diseases to which they have established immunity, either through evolution or through prior exposure. The arrival of a new population in the midst of an existing one will provoke exposure of each community to the other’s diseases. Small children back at school are prone to picking up all kinds of infections for exactly this reason.

So, the displacement of people from one country to another is a problem for the second country and not only for the first. The build-up of refugees from Bangladesh in India was a major reason for the latter’s intervention in the Pakistan civil war in 1971. A civil war is not only a problem for the country in which it takes place, but it is a problem for the region.

In addition to disease, there is also economic growth. A prosperous country is also a good trading partner. Paul Collier reports data to suggest that for every percentage point of growth among its neighbours, a country will on average experience 0.4 per cent growth itself as a result. This is a very powerful finding. The economic policies of a country are not merely a domestic concern but also an international concern. You see why federalists are interested in improving the way in which international considerations are factored into economic policy-making.

The famous principle of subsidiarity suggests that matters should be centralised if and only if they cannot be dealt with effectively at a lower level of government. We start to see that economic policy is not so obviously a national competence after all. The world shouldn’t be purely made up of states because it is not purely made up of states’ interests.